The invention relates to a device for pressing a rack onto a pinion.
Document EP 0 680 430 B1 makes known a device for pressing a rack onto a pinion engaged with the rack, in particular for a steering system of a motor vehicle, wherein, in order to eliminate or adjust the pressure piece play, component tolerances of the pinion, the rack, the housing, and the pressure piece are eliminated and specified pressure piece play is set by way of a selective installation of various retaining rings having different thicknesses. A gradation of 0.05 mm is usually utilized, which means that, given possible tolerance ranges of approximately 0.5 to 1 mm, a large number of various retaining rings having graduated thicknesses is necessary. A further disadvantage is that adjustments required due to wear and creep deformation of individual parts are not easily possible during operation.
A device for pressing a rack, in which existing tolerances can be easily eliminated and specified pressure piece play can be set, was therefore proposed in the older patent application DE 10 2008 054 782.4.
In order to compensate for tolerance, an adjusting device having two adjusting disks is provided, said adjusting disks being rotatable relative to one another and bearing against one another at contact surfaces, wherein the contact surfaces have at least two beveled edges. The two adjusting disks can be braced against one another by way of a torsion spring disposed therebetween, thereby making it possible to compensate for tolerances of the individual components.
The adjusting device further comprises a spring washer, which is disposed between the pressure piece and the first of the two adjusting disks facing the pressure piece. A shoulder is provided therefor, wherein this shoulder is provided in the pressure piece or on the adjusting disk and the other part has a recess. The shoulder of the adjusting device or the pressure piece results in play that is at least great enough, for example, to compensate for irregularities on the toothing between a pinion and a rack, the out-of-roundness of the pinion, or other nonconformities. The recess in the pressure piece or in the adjusting device allows the spring washer to have the range of spring it requires in order to compensate for the aforementioned play.
According to the older application, the adjusting device having the two adjusting disks and the torsion spring is designed as an assembly unit, wherein the two adjusting disks are fastened to one another by way of a screw and are prevented from rotating. After the subsequent installation of the compression spring, the adjusting screw is tightened with a certain amount of torque, thereby bridging the play achieved via the shoulder. Next, the adjusting disk is reopened by a certain angle, wherein the angle of opening should correspond to the play achieved via the shoulder. Finally, the adjusting screw must be safeguarded against rotation, for example via caulking or bonding.
The present invention is based on a further improvement of the older application, in particular a simpler assembly, wherein the advantages related to specified pressure piece play and tolerance compensation should be retained.